1. Technical Field
This application relates to UMTS (Universal Mobile Telecommunications System) in general, and to a method and apparatus for setting an integrity protection uplink application time for signalling bearer RB0 in a universal mobile telecommunications system in particular.
2. Description of the Related Art
UMTS is a third generation public land mobile telecommunication system. Various standardization bodies are known to publish and set standards for UMTS, each in their respective areas of competence. For instance, the 3GPP (Third Generation Partnership Project) has been known to publish and set standards for GSM (Global System for Mobile Communications) based UMTS, and the 3GPP2 (Third Generation Partnership Project 2) has been known to publish and set standards for CDMA (Code Division Multiple Access) based UMTS. Within the scope of a particular standardization body, specific partners publish and set standards in their respective areas.
Consider a wireless mobile device, generally referred to as user equipment (UE), that complies with the 3GPP specifications for the UMTS protocol. The 3GPP 25.331 specification, v.3.16.0, referred to herein as the 25.331 specification, addresses the subject of UMTS RRC (Radio Resource Control) protocol requirements between the UMTS Terrestrial Radio Access Network (UTRAN) and the UE.
Section 8.5.10 of the 25.331 specification describes integrity protection for RRC connections. The information element IE ‘Integrity protection mode info’ defines a new integrity protection configuration. Section 8.6.3.5.3 defines the setting of the uplink activation time for integrity protection for signalling radio bearer RB0, and is applicable for each of the SECURITY MODE COMMAND, RECONFIGURATION AND CELL UPDATE CONFIRM procedures. The activation time is the time, expressed in terms of a sequence number SN, at which a new integrity protection configuration is to be applied for signalling radio bearer RB0. In each of these cases, sections 8.1.12.3, 8.2.2.3 and 8.3.1.6 respectively state that when each procedure completes, the uplink message sequence number for radio bearer RB0 should be increased to a value such that the next RRC message to be sent on uplink RB0 will use the new integrity protection configuration.
The UTRAN MOBILITY INFORMATION procedure is a further procedure which may change the integrity protection configuration. However, the setting of the uplink message sequence number for this procedure is undefined, so that a new integrity protection configuration on RB0 may not be used for quite some time, thus compromising the security of the system.